A conventional saddle riding vehicle is known wherein a drive motor 60 provided in an electric power steering device is disposed so as to extend from a steering shaft side toward an outside in a vehicle width direction. See, for example, Japanese Patent Laid-Open No. 2004-231011.
As shown in FIG. 3 of Japanese Patent Laid-Open No. 2004-231011, the drive motor 60 of the electric power steering device extends substantially toward a side of the vehicle from the steering shaft 50 side with the steering shaft 50 being present on a vehicle body centerline A extending in a longitudinal direction of a vehicle, and reaching above an upper front suspension arm member 25 supported by a vehicle body frame.
When the drive motor 60 is disposed so as to extend toward the side of the vehicle, a center of gravity of the drive motor 60 separates from the vehicle body centerline A toward the side of the vehicle. Moreover, a center of gravity position of the drive motor 60 substantially coincides with a position of the upper front suspension arm member 25 in the longitudinal direction of the vehicle, that is, a position of an axle of front wheels. Since the drive motor 60 is a heavy object, a center of gravity of the vehicle body also separates from the vehicle body centerline A toward the side of the vehicle. This affects a right and left balance of the vehicle body, and also affects a weight distribution to the front and rear wheels.
It is desirable that the center of gravity of the vehicle body be located on the vehicle body centerline, and it is desirable that the center of gravity of the heavy object such as the electric motor be located between the axle of the front wheels and an axle of the rear wheels.
In addition, Japanese Patent Laid-Open No. 2004-231011 discloses a conventional electric power steering device support structure of a vehicle wherein upper and lower portions of an electric power steering device are supported by bearings.
As shown in FIG. 4 of Japanese Patent Laid-Open No. 2004-231011, a steering shaft 50 includes an upper shaft 50a and a lower shaft 50b that are coupled to each other by a universal joint 51. The upper shaft 50a is freely rotatably attached through a shaft support member 52 to an upper bracket 53 bridged between right and left upper pipes 18. The lower shaft 50b is freely rotatably attached through a gear case 55 to a lower bracket 54 bridged between right and left front suspension support portions 23b of a front cross pipe 23.
The universal joint 51 is disposed between the shaft support member 52 and the gear case 55.
Since the universal joint 51 includes a pair of yokes, an overall length of the steering shaft 50 is lengthened. Moreover, in the case of assembling the electric power steering device and the steering shaft 50 to a vehicle body frame, first, the lower shaft 50b is temporarily attached to the lower bracket 54 together with the gear case 55, and next, an upper end of the universal joint 51 that is coupled to the lower shaft 50b is coupled to the upper shaft 50a. In this case, since an upper portion of the universal joint 51 bends, the upper shaft 50a must be coupled thereto while holding the upper portion of the universal joint 51. This arrangement is poor in assembling workability. Furthermore, the weight of the steering shaft 50 is increased by using the universal joint 51 as compared with use of a simple shaft.